Dictionary · NIST SP 800-57 Part 1

Two or more distinct inputs produce the same output. Also see Hash Function.

1) Operations performed in defeating cryptographic protection without an initial knowledge of the key employed in providing the protection. 2) The study of mathematical techniques for attempting to defeat cryptographic techniques and information system security. This includes the process of looking for errors or weaknesses in the implementation of an algorithm or of the algorithm itself.

A cryptographic key that is generated for each execution of a key establishment process and that meets other requirements of the key type (e.g., unique to each message or session). In some cases, ephemeral keys are used more than once within a single session (e.g., broadcast applications) where the sender generates only one ephemeral key pair per message, and the private key is combined separately with each recipient’s public key.

A non-automated means of transporting cryptographic keys by physically moving a device, document, or person containing or possessing the key or key component.

A cryptographic key, used with a public key cryptographic algorithm, that is uniquely associated with an entity and is not made public. In an asymmetric (public) cryptosystem, the private key is associated with a public key. Depending on the algorithm, the private key may be used, for example, to: 1) Compute the corresponding public key, 2) Compute a digital signature that may be verified by the corresponding public key, 3) Decrypt keys that were encrypted by the corresponding public key, or 4) Compute a shared secret during a key-agreement transaction.

A cryptographic key, used with a public key cryptographic algorithm, that is uniquely associated with an entity and may be made public. In an asymmetric (public) cryptosystem, the public key is associated with a private key. The public key may be known by anyone and, depending on the algorithm, may be used, for example, to: 1) Verify a digital signature that is signed by the corresponding private key, 2) Encrypt keys that can be decrypted by the corresponding private key, or 3) Compute a shared secret during a key-agreement transaction.

The period of time during the cryptoperiod of a symmetric key when protected information is processed.

A cryptographic key that is used with a secret-key (symmetric) cryptographic algorithm that is uniquely associated with one or more entities and is not made public. The use of the term “secret” in this context does not imply a classification level, but rather implies the need to protect the key from disclosure.

A communication protocol that provides the appropriate confidentiality, authentication, and content-integrity protection.

The use of a digital signature algorithm and a public key to verify a digital signature on data.

Uses a digital signature algorithm and a private key to generate a digital signature on data.

A procedure by which a cryptographic key is split into n multiple key components, individually providing no knowledge of the original key, which can be subsequently combined to recreate the original cryptographic key. If knowledge of k (where k is less than or equal to n) components is required to construct the original key, then knowledge of any k-1 key components provides no information about the original key other than, possibly, its length.

A key that is intended for use for a relatively long period of time and is typically intended for use in many instances of a cryptographic key establish scheme

A public key and the name of a certification authority that is used to validate the first certificate in a sequence of certificates. The trust anchor’s public key is used to verify the signature on a certificate issued by a trust anchor certification authority. The security of the validation process depends upon the authenticity and integrity of the trust anchor. Trust anchors are often distributed as self-signed certificates.

An event involving the exposure of information to entities not authorized access to the information.

A function in the life cycle of keying material; the process whereby a user initializes its cryptographic application (e.g., installing and initializing software and hardware).

A function in the life cycle of keying material; a process whereby an entity becomes a member of a security domain.

The X.509 public-key certificate or the X.509 attribute certificate, as defined by the ISO/ITU-T X.509 standard. Most commonly (including in this document), an X.509 certificate refers to the X.509 public-key certificate.

A digital certificate containing a public key for entity and a name for the entity, together with some other information that is rendered unforgeable by the digital signature of the certification authority that issued the certificate, encoded in the format defined in the ISO/ITU-T X.509 standard.